Arthrodesis surgical apparatus and method

ABSTRACT

An arthrodesis surgical method and apparatus. After a guide pin is inserted into the joint to be fused, a core saw creates a cored-out cavity in the joint to be fixated. An autograft bone core is harvested with a core saw and is inserted into the cored-out cavity. The joint is then immobilized for the healing process.

FIELD OF INVENTION

This apparatus relates to fusion of joints, and more particularly to amethod and apparatus for simplifying and stabilizing the alignment ofthe adjacent bones in the joint and decreasing the time and effortrequired for the procedure.

BACKGROUND OF THE INVENTION

Surgical immobilization of a joint by fusion of adjacent bones is awell-established procedure. Artificial induction of joint ossificationbetween two bones by surgical means is employed to relieve intractablepain caused by one or more of several possible occurrences, includingfractures, severe sprains, and arthritis.

Such procedures are most commonly performed on joints in the hand,ankle, foot, and spine.

Metal implants can be attached to the two bones to hold them together ina position to enable permanent immobilization through bone growth, thatis, by bone fusion.

Arthrodesis procedures have presented challenges, starting from initialpositioning of a core saw prior to coring out the bones to be fused.Then maintaining the apparatus in alignment and position as theprocedure progresses. These procedures have, in some instances, resultedin malunion and non-union problems.

SUMMARY

It is a purpose of this apparatus and method to alleviate the challengesidentified above, among others. This is a greatly improved yetsimplified apparatus and technique to correct simple and severedeformities and fuse arthritic joints relatively easily and accurately.

This arthrodesis surgical apparatus consists of reciprocal sizes ofcannulated core saws, dedicated different sized cannulated plungers thatgo inside the cannulated saw, guide pin, and depth gauge. Thearthrodesis surgical apparatus has a very dramatic superior ability instreamlining, simplifying, improving reproducible results, decreasingsurgical procedure time, shortening of fusion consolidation/recoverytime, and decreasing malunion/non-union problems. It significantlydecreases the challenges of obtaining desirable orthopedic andbiomechanical reduction of foot and ankle valgus and varus deformities,for example.

BRIEF DESCRIPTION OF THE DRAWING

The objects, advantages, and features of this concept will be more fullyunderstood from the following detailed description, when read inconjunction with the accompanying drawing, in which:

FIG. 1 is a perspective view of the apparatus according to an embodimentof the invention;

FIG. 2 is a similar perspective view of the cannulated saw portion ofthe FIG. 1 apparatus;

FIG. 3 is a similar perspective view of the cannulated plunger of theFIG. 1 apparatus;

FIG. 4 is a side view of the guide pin of the FIG. 1 apparatus;

FIG. 5 is a perspective view of a cannulated depth gauge employed withthe guide pin of FIG. 4;

FIG. 6 is a schematic representation of the first step in an arthrodesissurgical procedure;

FIG. 7 is a schematic representation of the beginning of the second stepin an arthrodesis procedure in accordance with the present method;

FIG. 8 is a representation of the second step from FIG. 7;

FIG. 9 is a schematic representation of the third step of the presentmethod;

FIG. 10 is a schematic representation of the final step in this method;and

FIG. 11 shows the completion of this method.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

With reference now to the drawing, and more particularly to FIGS. 1-5,apparatus 11 includes core saw 12, through which extends cannulatedplunger stem 13, through which extends guide pin 14. Cannulated depthgauge 17 extends over guide pin 14 and is employed after the joint isX-rayed to determine proper positioning. This measurement is used todetermine the proper depth of the hole to be formed in the adjacentbones and tissues of the joint to be fused. Calibration lines 21 areshown on the surface of the depth gauge to provide a measure of theproper depth and is used to create the autograft core.

The technique involves first manipulating the joint into the desiredorthopedic position and then inserting K-wire 25 into the joint 24 to befused (FIG. 6). X-rays are taken to make sure the pin and the jointelements are in the desired position. The K-wire assures final desiredposition and alignment of the bones prior to the arthrodesis surgicalprocedure. Guide pin 14 is then inserted into the joint (FIGS. 7 and 8).To insert the guide pin it is fitted to a drill bit, typically part of apower drill, and it bores its way into the joint to a position as shownin FIG. 8. While the depth gauge is normally used, it is optional in thepractice of this procedure.

With reference to FIG. 9, cannulated plunger 10 on one end of plungerstem 13 is inserted into the desired size sawtooth head end 15 ofcannulated core saw 12 which is loaded on a suitable powered drillinghand piece. The cannulated plunger is inserted over the guide pin andthen the joint is cored out by teeth 15 using the powered drilling handpiece for rotation. When core saw 12 and plunger 10 are removed, boneand cartilage material comprise a plug that is removed at the same time.

Whichever size of this cored out deficit diameter is, a reciprocallarger core saw is used with the same guide pin/cannulated plungertechnique to harvest an autograft core 28 from either the calcaneus ortibia of the patient. The inner diameter of the autograft core saw headwill be about 0.3 mm larger than the diameter of the deficit at thefusion site. This is so there will be a slight press fitting of theharvested autograft core 28. The autograft of bone will need to betapped into the fusion site gently with a known bone tamp tool 29, asshown in FIG. 10. Once this has been accomplished the surgeon will thenimmobilize/stabilize the fusion site with their hardware of choice, thatis, cannulated screws or locking plate and screw construct. Theautograft deficit site will typically be backfilled with the surgeon'sallograft of choice.

The cannulated core saw sizes may vary approximately from about 3 mm toabout 14 mm depending on the size of the joint to be fused. Saws may bemuch larger depending on the size of the joint. Graduations 18 are shownon the surface of the core saw. They may be spaced as desired and in anysuitable units of measurements. The same is true of the calibrationlines 21 on depth gauge 17.

As mentioned above, the cannulated core saws will come in pairs. If thejoint to be fused has a deficit of 10 mm, for example, then thecannulated core saw used to harvest the autograft will have an innerdiameter of about 10.3 mm so that the autograft is slightly larger thanthe cored out fusion site. Likewise, if the fusion site is only a 6 mmdiameter deficit, the inner diameter of the autograft cannulated corewill be about 6.3 mm. Many different sizes can be created with thistechnique depending on how large the joint to be fused is. As anexample, for fusing the first metatarsal phalangeal joint the core sawmay be around 10 mm in diameter. For ankle or midfoot fusions, it may besmaller or larger in size. This also may have application for fusions ofthe hand, upper extremity, and even the spine.

Materials that the arthrodesis surgical device can be constructed of mayvary depending on practicality of production and sales. PEKK (polyethylketone ketone) is very hearty, durable, and cost-effective materialwhich would be practical for one-time usage. However, metal materialwould also work. PEEK (polyethyl ethyl ketone) may also be consideredbut it is a more expensive material.

What is claimed:
 1. Apparatus to facilitate fusion of bone joints, theapparatus comprising: an elongated, cannulated core saw device havingsaw teeth at one end, said core saw device being open ended and hollowthroughout its length, the opposite end of said core saw device beingengageable by a drill bit of a power drill; an elongated, cannulatedplunger which has a stem configured to extend through and is longer thansaid hollow core saw device, said plunger being sized to fit within theend of said core saw device within said saw teeth; and an elongatedguide pin which is configured to extend through and is longer than saidplunger; said guide pin, said plunger, and said core saw device beingcoaxial; after said guide pin is inserted into a joint to be fused, saidplunger is inserted over said guide pin and said core saw device isinserted over said plunger and said core saw device is rotated to coreout adjacent bones and cartilage to form a core opening configured toreceive an autograft core.
 2. The apparatus of claim 1, and furthercomprising an elongated, cannulated depth gauge within which said guidepin extends.
 3. The apparatus of claim 1, wherein said core saw devicecomprises two saw tooth heads, one size for creating the autograft coreand a smaller size head for creating cored out material from the jointto be fused.
 4. The apparatus of claim 3, wherein a diameter differenceof the saw tooth heads is about 0.3 mm.
 5. A method for facilitatingbone joint fusion, comprising: inserting a K-wire diagonally through ajoint to be fused to stabilize the joint; inserting an elongated guidepin in a joint at the location of the fusing; inserting an elongated,cannulated plunger over the guide pin; inserting an elongated core sawdevice over the plunger, a core saw device having a first core saw headof a first diameter and a second core saw head of a second, largerdiameter; rotating the first core saw head of the core saw device toremove bone and cartilage material to form a cylindrical hole in thejoint to be fused; removing thus cored out material; removing the coresaw device, guide pin, and plunger from the joint to be fused;harvesting an autograft bone core from the patient; and inserting theautograft bone core into the cored out hole created by removing the boneand cartilage material.
 6. The method of claim 5, and further comprisingmeasuring a depth of the joint to be fused by means of a depth gaugeinserted into the joint over the guide pin.
 7. The method of claim 5,wherein the autograft bone core is harvested using the second core sawhead larger in diameter than the first core saw head.
 8. The method ofclaim 7, wherein said second core saw head is about 0.3 mm larger thansaid first core saw head.